Eliminated compiler warnings

[bjoo]

I added some patches to eliminate compiler warnings. Most came from unused variables, so I defined a macro to magic those away. Then there were. a bunch of:

if( foo ) 
  QMP_printf(...) ; fflush(stdout);

which tripped the misleading indentation warning so I changed these up with {} as

if (foo) { 
 QMP_printf(...) ; fflush(stdout);
}

The other things were comparisons between signed and unsigned ints. So I tried to make these work.
Please review and merge.

[mathiaswagner]

This seems to build from lattice/quda#1156 without warnings now. Thanks @bjoo !